The present invention relates to a liquid ejecting head for ejecting desired liquid by generation of bubble by application of thermal energy thereto, a head cartridge using the liquid ejecting head, a liquid ejecting apparatus and a liquid ejecting method.
More particularly, the present invention relates to a liquid ejecting method, a liquid ejecting head, a head cartridge using the liquid ejecting head, and a liquid ejecting apparatus, using a movable member which displaces by generation of a bubble.
The present invention is applicable to equipment such as a printer, a copying machine, a facsimile machine having a communication system, a word processor having a printer portion or the like, and an industrial recording device combined with various processing device or processing devices, in which the recording is effected on a recording material such as paper, thread, fiber, textile, leather, metal, plastic resin material, glass, wood, ceramic and so on.
In this specification, xe2x80x9crecordingxe2x80x9d means not only forming an image of letter, figure or the like having specific meanings, but also includes forming an image of a pattern not having a specific meaning.
An ink jet recording method of so-called bubble jet type is known in which an instantaneous state change resulting in an instantaneous volume change (bubble generation) is caused by application of energy such as heat to the ink, so as to eject the ink through the ejection outlet by the force resulted from the state change by which the ink is ejected to and deposited on the recording material to form an image formation. As disclosed in U.S. Pat. No. 4,723,129, a recording device using the bubble jet recording method comprises an ejection outlet for ejecting the ink, an ink flow path in fluid communication with the ejection outlet, and an electrothermal transducer as energy generating means disposed in the ink flow path.
With such a recording method is advantageous in that, a high quality image, can be recorded at high speed and with low noise, and a plurality of such ejection outlets can be posited at high density, and therefore, small size recording apparatus capable of providing a high resolution can be provided, and color images can be easily formed. Therefore, the bubble jet recording method is now widely used in printers, copying machines, facsimile machines or another office equipment, and for industrial systems such as textile printing device or the like.
With the increase of the wide needs for the bubble jet technique, various demands are imposed thereon, recently.
For example, an improvement in energy use efficiency is demanded. To meet the demand, the optimization of the heat generating element such as adjustment of the thickness of the protecting film is investigated. This method is effective in that a propagation efficiency of the generated heat to the liquid is improved.
In order to provide high image quality images, driving conditions have been proposed by which the ink ejection speed is increased, and/or the bubble generation is stabilized to accomplish better ink ejection. As another example, from the standpoint of increasing the recording speed, flow passage configuration improvements have been proposed by which the speed of liquid filling (refilling) into the liquid flow path is increased.
Japanese Laid Open Patent Application No. SHO-63-199972 and so on discloses a flow passage structure shown in FIG. 34, (a), (b).
On the other hand, in the bubble jet recording method, the heating is repeated with the heat generating element contacted with the ink, and therefore, a burnt material is deposited on the surface of the heat generating element due to burnt deposit of the ink. However, the amount of the deposition may be large depending on the materials of the ink. If this occurs, the ink ejection becomes unstable. Additionally, even when the liquid to be ejected is the one easily deteriorated by heat or even when the liquid is the one with which the bubble generation is not sufficient, the liquid is desired to be ejected in good order without property change.
Japanese Laid Open Patent Application No. SHO-61-69467, Japanese Laid Open Patent Application No. SHO-55-81172 and U.S. Pat. No. 4,480,259 disclose that different liquids are used for the liquid generating the bubble by the heat (bubble generating liquid) and for the liquid to be ejected (ejection liquid). In these publications, the ink as the ejection liquid and the bubble generation liquid are completely separated by a flexible film of silicone rubber or the like so as to prevent direct contact of the ejection liquid to the heat generating element while propagating the pressure resulting from the bubble generation of the bubble generation liquid to the ejection liquid by the deformation of the flexible film. The prevention of the deposition of the material on the surface of the heat generating element and the increase of the selection latitude of the ejection liquid are accomplished, by such a structure.
However, with this structure in which the ejection liquid and the bubble generation liquid are completely separated, the pressure by the bubble generation is propagated to the ejection liquid through the expansion-contraction deformation of the flexible film, and therefore, the pressure is absorbed by the flexible film to a quite high degree. In addition, the deformation of the flexible film is not so large, and therefore, the energy use efficiency and the ejection force are deteriorated although the some effect is provided by the provision between the ejection liquid and the bubble generation liquid.
Accordingly, it is a principal object of the present invention to provide a liquid ejecting head and device wherein the state of the liquid to be ejected is changed at least upon the start of the recording operation, while maintaining the high ejection power and the high ejection efficiency, by which ejection performance and the property for the recording material are improved or normalized to stabilize and improve the image quality.
It is another object of the present invention to provide a liquid ejecting head and a device, wherein ejection liquid and/or the bubble generation liquid is discharged at the latest upon the record start, and the density of the ejection liquid is stabilized to improve or stabilize the image quality.
It is a further object of the present invention to provide a liquid ejecting head, a driving method therefor, and a device, wherein selection latitude of the liquid to be ejected is enhanced, while maintaining the stability of the ejection property and the high recorded image quality.
According to an aspect of the present invention, there is provided a liquid ejecting method for ejecting liquid using a bubble, comprising the steps of: using a liquid ejecting head having an ejection outlet for ejecting the liquid, a bubble generating region where a bubble is generated in the liquid, a movable member which is disposed faced to said bubble generating region, and which is displaceable between a first position and a second position farther from the bubble generating region than the first position and which has a free end at a downstream side thereof;
displacing the movable member from said first position to said second position by pressure based on generation of the bubble in said bubble generating region, wherein said bubble expands more to the downstream side than to the upstream side with respect to a direction toward said ejection outlet by the displacement of said movable member, thus directing said bubble toward said ejection outlet to eject the liquid through the ejection outlet; and
imparting an operation to said liquid ejecting head to normalize a state of the liquid in a liquid flow path for the liquid at least before liquid ejection start or at the time of non-ejection of the liquid.
According to another aspect of the present invention, there is provided a liquid ejection apparatus, using a liquid ejection head having an ejection outlet for ejecting the liquid, a bubble generating region where a bubble is generated in the liquid, a movable member which is disposed faced to said bubble generating region, and which is displaceable between a first position and a second position farther from the bubble generating region than the first position and which has a free end at a downstream side thereof;
wherein the movable member is displaced from said first position to said second position by pressure based on generation of the bubble in said bubble generating region, wherein said bubble expands more to the downstream side than to the upstream side with respect to a direction toward said ejection outlet by the displacement of said movable member, thus directing said bubble toward said ejection outlet to eject the liquid through the ejection outlet; the improvement comprising:
driving means for imparting an operation to said liquid ejecting head to normalize a state of the liquid in a liquid flow path for the liquid at least before liquid ejection start or at the time of non- ejection of the liquid.
According to a further aspect of the present invention, there is provided a liquid ejecting head for ejecting liquid using a bubble, comprising:
an ejection outlet for ejecting the liquid:
a bubble generating region for generating the bubble in the liquid:
a movable member which is disposed faced to said bubble generating region, and which is displaceable between a first position and a second position farther from the bubble generating region than the first position and which has a free end at a downstream side thereof;
wherein the movable member is displaced from said first position to said second position by pressure based on generation of the bubble in said bubble generating region, wherein said bubble expands more to the downstream side than to the upstream side with respect to a direction toward said ejection outlet by the displacement of said movable member, thus directing said bubble toward said ejection outlet to eject the liquid through the ejection outlet; and
means for changing a state of said liquid by changing a temperature of said liquid.
According to a further aspect of the present invention, there is provided a liquid ejecting head for ejecting liquid using a bubble, comprising:
an ejection outlet for ejecting the liquid:
a bubble generating region for generating the bubble in the liquid:
a movable member which is disposed faced to said bubble generating region, and which is displaceable between a first position and a second position farther from the bubble generating region than the first position and which has a free end at a downstream side thereof;
wherein the movable member is displaced from said first position to said second position by pressure based on generation of the bubble in said bubble generating region, wherein said bubble expands more to the downstream side than to the upstream side with respect to a direction toward said ejection outlet by the displacement of said movable member, thus directing said bubble toward said ejection outlet to eject the liquid through the ejection outlet; and
liquid moving means for changing a state of said liquid by moving said liquid without ejecting said liquid.
According to a further aspect of the present invention, there is provided a liquid ejection apparatus for ejecting liquid, comprising:
a liquid ejecting head having an ejection outlet for ejecting the liquid, a bubble generating region where a bubble is generated in the liquid, a movable member which is disposed faced to said bubble generating region, and which is displaceable between a first position and a second position farther from the bubble generating region than the first position and which has a free end at a downstream side thereof;
wherein the movable member is displaced from said first position to said second position by pressure based on generation of the bubble in said bubble generating region, wherein said bubble expands more to the downstream side than to the upstream side with respect to a direction toward said ejection outlet by the displacement of said movable member, thus directing said bubble toward said ejection outlet to eject the liquid through the ejection outlet; and
energy increasing means for making larger bubble generation energy for ejecting at least during a predetermined period from ejection start than thereafter.
According to a further aspect of the present invention, there is provided a liquid ejecting method for ejecting liquid using a bubble, comprising:
using a liquid ejecting head having an ejection outlet for ejecting the liquid, a bubble generating region where a bubble is generated in the liquid, a movable member which is disposed faced to said bubble generating region, and which is displaceable between a first position and a second position farther from the bubble generating region than the first position and which has a free end at a downstream side thereof;
wherein the movable member is displaced from said first position to said second position by pressure based on generation of the bubble in said bubble generating region, wherein said bubble expands more to the downstream side than to the upstream side with respect to a direction toward said ejection outlet by the displacement of said movable member, thus directing said bubble toward said ejection outlet to eject the liquid through the ejection outlet; and
making larger bubble generation energy for ejecting at least during a predetermined period from ejection start than thereafter.
According to a further aspect of the present invention, there is provided a liquid ejecting apparatus for effecting recording by ejecting liquid, comprising:
a liquid ejecting head having an ejection outlet for ejecting the liquid, a bubble generating region where a bubble is generated in the liquid, a movable member which is disposed faced to said bubble generating region, and which is displaceable between a first position and a second position farther from the bubble generating region than the first position and which has a free end at a downstream side thereof;
wherein the movable member is displaced from said first position to said second position by pressure based on generation of the bubble in said bubble generating region, wherein said bubble expands more to the downstream side than to the upstream side with respect to a direction toward said ejection outlet by the displacement of said movable member, thus directing said bubble toward said ejection outlet to eject the liquid through the ejection outlet; and
discharging means for discharging said liquid from the liquid flow path for the liquid to be ejected during a predetermined period in a non-ejection period at least before ejection start, using means partly constituting said liquid ejecting head.
means for changing a state of said liquid by changing a temperature of said liquid,
liquid moving means for changing a state of said liquid by moving said liquid without ejecting said liquid; and
energy increasing means for making larger bubble generation energy for ejecting at least during a predetermined period from ejection start than thereafter.
In this specification, xe2x80x9cupstreamxe2x80x9d and xe2x80x9cdownstreamxe2x80x9d are defined with respect to a general liquid flow from a liquid supply source to the ejection outlet through the bubble generation region (movable member).
As regards the bubble per se, the xe2x80x9cdownstreamxe2x80x9d is defined as toward the ejection outlet side of the bubble which directly function to eject the liquid droplet. More particularly, it generally means a downstream from the center of the bubble with respect to the direction of the general liquid flow, or a downstream from the center of the area of the heat generating element with respect to the same.
In this specification, xe2x80x9csubstantially sealedxe2x80x9d generally means a sealed state in such a degree that when the bubble grows, the bubble does not escape through a gap (slit) around the movable member before motion of the movable member.
In this specification, xe2x80x9cseparation wallxe2x80x9d may mean a wall (which may include the movable member) interposed to separate the region in direct fluid communication with the ejection outlet from the bubble generation region, and more specifically means a wall separating the flow path including the bubble generation region from the liquid flow path in direct fluid communication with the ejection outlet, thus preventing mixture of the liquids in the liquid flow paths.
In this specification, xe2x80x9cupon xe2x80x2non-ejectionxe2x80x2, xe2x80x2non-printingxe2x80x2 or xe2x80x2non-recordingxe2x80x2xe2x80x9d, means xe2x80x9cwhen the liquid is not ejected for a period longer than a minimum ejection period (a reciprocal of the maximum ejection frequency) of repeated liquid ejections by bubble generations for the recording operation, in a nozzle. For example, it occurs in the not recording range in one line recording in a serial printer, in the sheet advancing period between lines, in the sheet feeding period between pages, in a temporary rest period waiting for recording instructions from a host computer, or in the off-state of the voltage source. Thus, it may mean a short or long period.
In this specification, xe2x80x9cupon xe2x80x2ejection startxe2x80x2, xe2x80x2print startxe2x80x2, or xe2x80x2record startxe2x80x2xe2x80x9d, covers a short period from start or resumption of the ejection, printing or recording after the non-ejection of a certain period.
While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims.